Cataract

What are cataracts?

The lens of the eye is a biconvex, normally transparent structure behind the pupil. It focuses light rays into images on the retina, the light-sensitive lining at the back of the eye. A cataract is opacity or clouding of the lens. It prevents the lens from focussing light onto the retina, hence, causing hazy vision. Aging and other factors may cause the proteins in the lens to degenerate, forming opaque (cloudy) areas. They usually develop slowly over several years and are irreversible. As the cataract advances, the cloudiness of vision increases over a period of time until the vision is completely impaired. Advanced cataract can cause blindness, but they can be successfully treated with surgery.

What causes cataracts?

Although age-related changes are the primary cause of cataract formation, these can be affected by other factors. These include free-oxygen radicals, ultraviolet radiation, smoking, alcohol, steroids, drugs like psoralens, tamoxifen, phenothiazines, amiodarone, and mepacrine.

Medical disorders such as diabetes, glaucoma, and certain metabolic conditions, can also contribute to their formation. Physical injury to the eye (such as a hard blow, cut, or puncture), intense heat or cold, chemical burns, or radiation therapy can also cause cataracts. Rarely, a baby is born with a congenital cataract, usually because of an infection during pregnancy or an inherited disorder. The closer people live to the equator the greater the chance of developing cataracts.

How serious are cataracts?

According to the World Health Organization, cataracts are the leading cause of blindness around the world; an estimated 17 million people are visually impaired because of them. The severity of cataracts varies widely. When cataracts form at the outer edge of the lens, they may interfere very little with vision. Those located in the center of the lens, however, will cause significant vision loss.

What are the symptoms?

The symptoms of cataract are variable because they form in different ways. In most patients, the initial symptoms of cataracts are progressively cloudy vision, double vision, or both. Objects may begin to look yellow, hazy, blurred or distorted. People may experience increasing nearsightedness needing frequent change of eyeglasses. Others may find that they need more light to see clearly. Cataracts can cause other visual disturbances – decrease of colour vibrancy, difficulty in reading and coloured haloes around lights. People having diffuse cataracts in the rear walls of their lenses are more likely to experience glare, because their cataracts lead to scattering of light. In later stages the decrease of vision leads to blindness.

Can cataracts be prevented?

Cataracts that occur due to the aging process cannot be prevented as the aging process itself cannot be prevented. Using the eyes for reading and similar activities have nothing to do with cataract formation. Avoiding the use of eyes will not prevent cataract. Till date as per all authentic medical research, no medication exists to prevent or cure a cataract. The only known treatment for cataract is surgery.

How are cataracts diagnosed?

The doctor will check the vision and examine the lens for any signs of cataract. If the patient is having a significant visual handicap, the surgeon will advise surgery. In that case, a painless ultrasound test is done to measure the length of the eye and determine the power of replacement lens to be implanted during surgery.

What is the treatment?

Early cataracts, if they lead to near-sightedness, may be managed by prescribing stronger eyeglasses or contact lenses. No medical treatment can prevent or reverse the development of cataracts. Once a cataract develops, surgical removal is still the only remedy.

Cataract surgery is usually done as a day-care procedure under local anaesthesia and takes about half an hour. A cataract extraction with intra-ocular lens implantation is a procedure in which the cataract is replaced with an artificial lens implant.

What happens during the surgery?

The surgeon makes a small cut in the eye and removes the cloudy lens either by a routine cataract procedure or by phaco-emulsification. In phaco-emulsification, sound waves (ultrasound) are used to break the lens into small pieces, using a thin titanium probe. The small pieces can then be sucked out through the same probe. The surgeon will put a plastic lens (called an IOL – Intra Ocular Lens implant) in the eye. One or no stitch may be given and a patch put over the eye.

What happens after the procedure?

The patient is kept in the recovery area for about an hour after surgery. It is normal to feel slight itching, sticky eyelids, and mild discomfort for a while after cataract surgery. Some fluid discharge is also common.

Although, some activities are restricted after surgery, reading and watching TV is allowed right away. Simple tasks such as riding in a car, stooping over to put on shoes, resuming normal work, and visiting friends can be done. Water or other substances should not be allowed to get into the operated eye. Accidental pressure to the eye should be avoided. Eye-drops may be needed to help healing or to prevent infection or swelling. In most cases, it takes about 3-6 weeks for the eye to heal. New glasses can be worn after about a month.

What are the benefits of this procedure?

Cataract surgery is very successful. Nearly all patients enjoy better vision after surgery, unless they have other eye problems. There are numerous benefits of cataract surgery, many of which cannot be measured statistically. These include improved colour vision, greater clarity of vision, improved quality of life - people can resume driving, reading, writing, watching television, sewing, household work, and using a computer after the surgery.

What are the risks of this procedure?

Modern cataract surgery is one of the safest of all surgical procedures. However some minor complications that can occur include a slight drooping of the eyelid, swelling around the eye, corneal haze, reflections or slight distortion from the lens implant, which are usually temporary. The chances for serious complications are negligible. Possible serious complications include severe inflammation, glaucoma (high internal eye pressure), displacement of the implanted lens, haemorrhage, retinal detachment and infection. Some of these rare serious complications may cause poorer vision than before the surgery or even blindness in the operated eye.